pgsql: On Windows, we know the backend stack size limit because we have

Log Message:
-----------
On Windows, we know the backend stack size limit because we have to
specify it explicitly in backend/Makefile.  Arrange for this value to
be known by get_stack_depth_rlimit() too.  Per suggestion from Magnus.

Modified Files:
--------------
    pgsql/src:
        Makefile.global.in (r1.231 -> r1.232)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/Makefile.global.in.diff?r1=1.231&r2=1.232)
    pgsql/src/backend:
        Makefile (r1.119 -> r1.120)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/Makefile.diff?r1=1.119&r2=1.120)
    pgsql/src/backend/tcop:
        Makefile (r1.25 -> r1.26)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/Makefile.diff?r1=1.25&r2=1.26)
        postgres.c (r1.513 -> r1.514)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/tcop/postgres.c.diff?r1=1.513&r2=1.514)